How to understand 'HTTP/1.1 500 Internal Server Error' in EngageOne Server

Product Feature: API (Web Service, SDI, etc.)
An 'HTTP/1.1 500 Internal Server Error' can occur as in the example below when specifying an incorrect Template ID in the request XML in SOAP UI.

User-added image

Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has encountered an error or is otherwise incapable of performing the request. 
500 Internal Server Error is a generic error message, given when an unexpected condition was encountered and no more specific message is suitable.

Here, the SOAP UI client is requesting for the template and sends the request to the Server. Since the Server cannot find the template (due to an incorrect template id), the Server will result in this error HTTP 500. The error is generated by the Server and not by the Client. 
UPDATED:  November 15, 2017